Intelligent welding technology for multi-layer and multi-pass welding of pressure pipeline

Abstract To address the requirements of intelligent welding in multi-layer and multi-pass welding of pressure pipelines, this study establishes an integrated system combining automatic positioning with real-time weld formation monitoring. By employing line laser scanning, point cloud data is acquired to identify groove boundary endpoints, from which arc initiation and termination coordinates are calculated, thus realizing automated positioning. The welding path is planned according to the calculated groove cross-sectional area and that of a single weld bead. Throughout welding, both process parameters and weld formation dimensions are continuously monitored to ensure weld integrity. The system was validated through multi-layer and multi-pass welding trials on 30 mm thick Q345 steel pipes, achieving uniform and defect-free welds. Microstructural analysis revealed a ferrite–pearlite structure, with measured tensile strength of 559.5 MPa and elongation of 27.5%, meeting application performance criteria.